function newSum122() {
		randomnumber1 = getRandomInt(1, 9);
		randomnumber2 = getRandomInt(10, 99 - randomnumber1);
		right_ans = randomnumber1 + randomnumber2;
		temp_ans_rank = 2;
}

function newDif21() {
	randomnumber1 = getRandomInt(10, 99);
	randomnumber2 = getRandomInt(1, 9);
	right_ans = randomnumber1 - randomnumber2;
	if (right_ans > 9) temp_ans_rank = 2;
		else temp_ans_rank = 1;
}

function newSumDif21() {
	var operation_id = getRandomInt(1, 2);
	switch (operation_id) {
		case 1:
			operation = "Sum";
			operation_sign = "+";
			newSum122();
			break;
		case 2:
			operation = "Dif";
			operation_sign = "-";
			newDif21();
			break;
	}
}

function Start() {
	operation_sign = "no_op_sign";
	operation = "no_operation";
	operation_func = newSumDif21;
	left_rank = 2;
	right_rank = 1;
	ans_rank = -1;
	document.documentElement.addEventListener("keydown", keyHandler, false);
	timer();
	newTask(operation_func);
}

function getScore(right_count, wrong_count) {
	return 10*right_score - 15*wrong_score;
}